Method and apparatus for detecting measurement position of resonance sensor

In a resonance sensor 20, a measuring element 22 is resonant-vibrated in the longitudinal direction by vibrating means (a piezoelectric element 24), an output signal depending on resonance of the measuring element 22 is obtained by detecting means (a piezoelectric element 26), and a change in the output signal is captured, thereby sensing a contact between the tip end 22A of the measuring element and a measurement object 10. In detection of a measurement position of the resonance sensor, a characteristic curve showing a relationship between the distance between the measuring element 22 and the measurement object 10, and a change state of the output signal is obtained, and a change start position of the output signal corresponding to a contact start position is estimated from the characteristic curve, and set as a measurement position.